1. Field of the Invention
The present invention relates to a cable, and more particularly to a cable having EMI Suppressing Arrangement of a magnetic layer arranged to an outer surface of a shielding layer of the cable. The invention also relates to a method for making the same.
2. Description of the Prior Art
It is already known to provide a ferrite core on an outer surface of a cable assembly intermediate opposite ends thereof in order to suppress the electromagnetic-wave interference (EMI) during transmission of signal, especially at high speed transmission. Generally, the ferrite core is arranged on that portion of the cable assembly near to a connector terminated thereto. This portion of the cable assembly is covered from the exterior. In this configuration, EMI noises are prevented from intruding into the cable from the exterior, and also EMI noises are prevented from negatively effecting to a signal transmitted through a wire conductor therein.
However, an assembling operational process for securely attaching the ferrite core to the cable assembly is cumbersome, and also there are restrictions with respect to an increased mounting space, an increased weight, etc. As a result, the cost of the cable assembly increases. In addition, there is a fear that the ferrite core is damaged since it projects much from the cable.
In order to overcome these difficulties, a proposed solution has been provided that a second insulating layer of the cable assembly is provided on an outer surface of a shielding layer, and then an amorphous magnetic layer is provided on an outer surface of the second insulating layer at least over a given area thereof. In this cable assembly, a first insulating layer is provided on an outer surface of a conductor, and the shielding layer which is in the form of a braided metal wire is formed on an outer peripheral surface of the first insulating layer. The second insulating layer is formed on the outer surface of the shielding layer, and the amorphous magnetic layer is formed on the outer surface of the second insulating layer over an entire length thereof or over at least part of the length thereof. Typically disclosed in JP-A-6-203652, Pages 1 to 4, FIGS. 1 and 2.
The cable assembly, disclosed in the above patent publication, is more advantageous in view of the restrictions on the mounting space, the weight, etc., as compared with the cable having the ferrite core provided thereon. However, its effect of suppressing EMI noises has been low since a base tape of an amorphous magnetic tape, forming the amorphous magnetic layer, is made of polyester or PPS.
Hence, an improved EMI-suppressing cable is desired to overcome the above problems.